Abstract—Electric vehicle (EV) is an important solution for

the traffic and environment problems in cities. However, to plan

and build the energy supply and service network is always a

challenging work all over the world. This paper is based on the

planning of a real charge-swap service network for the electric

vehicle in Hangzhou city, China. First, this paper defined the

service radius for a network and developed the technical

evaluation model; second, the economic evaluation model is

proposed based mainly on the investment analysis considering

the operating cost and earnings of the network. A case study is

presented to show the application of the proposed evaluation

method for a real charge-swap service network with a

three-hierarchy structure.

Index Terms—Electric vehicles, planning, technical

evaluation, economic evaluation.

I. INTRODUCTION

At present, EVs have not been used widely in China and the

charge-swap facilities are severely lacking. But China will

make breakthrough in the near future. Reference [1] analyzed

the application of pure-electric vehicles in techno-economy

based on life-cycle cost theory, and compared pure-electric

vehicles with traditional oil-fuelled vehicles. In paper [2], the

author proposed the economic and environmental impacts of

regional widespread use of EV and offered models to analyze

how economically and environmentally sound for a region to

develop EVs. Reference [3] described the present

construction situation of charging facilities as well as its

development plan. The paper will develop technical and

economic evaluation model to measure the economic benefit

that the charge-swap service network provide for the service

company and the service performance that the charge-swap

service network provide for EVs users.

II. CHARGING NETWORK PLANNING EVALUATION FACTOR

ANALYSIS

A. Introduction of Charging Infrastructure

There are four types of facilities in charge-swap service

network: charging pile, battery-charging and

battery-swapping station(CSS), centralized battery-charging

station(CCS) and battery-swapping station(BSS), as

Manuscript received February 2, 2014; revised June 24, 2014.

Junhai Wang is with Hangzhou Power Supply Company in Zhejiang

Provincial Electric Power Company, Hangzhou, China (e-mail:

wanghdtv@263.net).

Lingling Ming and Dayang Yu are with Laboratory for the Synergistic

Dispatch of the Decentralized Electric Power Grid, Shandong University,

Jinan, China (e-mail: mingling0104@163.com, yudayang@sdu.edu.cn).

described next.

Electric vehicles which load chargers use the AC power for

electricity by charging piles and the rated power is under

5KW. Generally speaking, charging piles are mainly installed

on parking spaces such as underground garage of residential

areas, public parking lot and shopping mall.

CSS swap fully charged batteries for depleted ones for

electric vehicles and eliminate much of the waiting time. The

time of the process is only few minutes. CSS can charge the

depleted batteries collectively when the grid load is low and

can preserve batteries. There are three types of CSS based on

the scale of the size of CSS: 100 chargers stations, 200

chargers stations and 400 chargers stations. If it’s 100

chargers station, the station is equipped with 100 chargers to

charge batteries; 200 chargers station, the station is equipped

with 200 chargers; 400 chargers station, the station is

equipped with 400 chargers, and so on. The chargers can

charge batteries 5 times every day.

CCS and BSS provide energy services for electric vehicles

together. CCS charges depleted batteries centrally and carries

fully charged batteries for BSS 4 times every day. Then BSS

swap fully charged batteries for depleted ones for electric

vehicles. According to the experience of electric vehicle

market, CCS is usually equipped with 3000 chargers and

usually charge batteries 2 times every day. A CCS usually

carry batteries for 20~25 BSSs. CCS can carry 80 batteries for

BSS one time and BSS is supplemented with 4 carrier

vehicles to carry batteries.

B. Technology and Structure of Charging Network

Charging facility network has the mode of battery

swapping as the threads of technology. The paper presents the

EV charging facility network planning aimed at vehicles

which get energy by battery replacement.

There are tow types of charge-swap service network in the

paper: the two-tier structure service network and the three-tier

structure service network. The two-tier structure service

network is composed of charging pile and CSS and the

three-tier structure service network is composed of charging

pile, CSS, CCS and BSS. The three-tier structure service

network is developed from the two-tier structure service

network.

III. TECHNICAL EVALUATION MODEL OF CHARGE-SWAP

SERVICE NETWORK

The paper has the full-network service capability and the

service radius of the service network as the technical

evaluation indicators. The service ability of the whole

network should not be less than the charge-swap demand of

Technical and Economic Evaluation of the Electric Vehicle

Charging Network Planning Scheme

Junhai Wang, Lingling Ming, and Dayang Yu

Journal of Clean Energy Technologies, Vol. 3, No. 4, July 2015

317DOI: 10.7763/JOCET.2015.V3.215

EVs. The rationality of charge-swap service network is

related to the service radius. The service radius of

charge-swap service network must be less than the driving

range of Evs [4]. The service radius should ensure that the

service radius is less than 10%-20% of the driving range of

EVs [5].

A. The Service Ability of Charge-Swap Service Network

The service ability of charge-swap service network

depends on the type and the number of charge-swap facility

and the full-network charge-swap service utilization

coefficient. The charge-swap facility service network faces

the problem of shortage of service supply because of the

unreasonable layout of charging facilities from the whole

service network point. So the paper cites the full-network

service utilization coefficient to reduce the full-network

service capability.

.0i

n

HH FN (1)

where HN represents the actual full-network service ability

of battery replacement; HF represents actual service ability

of single station; denotes the full-network service

utilization coefficient of the battery swapping service and n

denotes the number of charge-swap facilities.

B. The Service Radius of Charge-Swap Service Network

The service radius of charge-swap service network should

meet the code for transport planning on urban road [6]. The

service radius is described below.

.14.3// nSR (2)

where R represents the service radius of charge-swap service

network; S denotes the area of planned district and n

denotes the number of charge-swap facilities.

IV. ECONOMIC EVALUATION MODEL OF CHARGE-SWAP

SERVICE NETWORK

The paper analyzes the life-cycle cost of charge-swap

service network. The life-cycle cost of charge-swap service

network mainly concludes battery investment, infrastructure

investment, associated power network investment, equipment

maintenance cost, battery transportation cost and labor cost

[7].

A. Charge-Swap Service Network Investment Analysis

The battery investment is described below.

.1

clxn

i

Sd PrC4S (3)

where dS represents battery investment; 4 denotes 4 denotes

4 batteries loaded in a electric vehicle; SC denotes the

number of one type of electric vehicle; r represents the

redundancy of the battery; P denotes the cost of every

battery and clxn denotes the number of the kinds of electric

vehicles.

The equipment maintenance cost of every facility accounts

for 2 percent of the investments of the infrastructure and the

associated power network. The battery transportation cost

every time is 400 yuan, and the total transportation cost every

year is 584000 yuan every BSS because that the CCS need to

transport batteries to the BSS 4 times every day.

The staff assignment of every facility is shown in Table I.

TABLE I: THE STAFF ASSIGNMENT OF EVERY FACILITY

Facility 100chargers station

The number of workers 12

200chargers station 400chargers station CCS BSS

15 18 12 6

Every employee is engaged at a salary of 50000 yuan a

year.

According to the present empirical data, the investments of

every facility are presented. (Shown in Table II).

TABLE II: THE INVESTMENTS OF EVERY FACILITY

(a)

Facility CSS

100 chargers station

Infrastructure investment(million) 8

Associated power network investment

(million) 0.8

Equipment maintenance cost(million) 0.116

Labor cost(million) 0.6

(b)

CSS CCS BSS

200 chargers station 400 chargers station

10 12 100 1

1.2 1.6 8 0

0.164 0.232 0.495 0.009

0.75 0.9 0.6 0.3

B. Charge-Swap Service Earnings Analysis

The EV service companies charge the user of EV by the

mileage because the mileage of electric vehicle is predictable.

.1

clxn

i

S RMCZ (4)

where Z represents the earning every year; SC denotes the

number of one type of electric vehicle; M represents the

mileage of electric vehicle every day; R denotes the number

of working days every year; denotes the service price per

kilometer and clxn denotes the number of type of electric

vehicles.

C. Operation Benefits Analysis of Charge-Swap Service

Network

The economic evaluation indicator can analyze and

evaluate the charge-swap service network planning. The

paper has the internal rate of return (IRR) and dynamic

investment pay-back period as the economic evaluation

indicators.

The net present value(NPV) is the present value of current

and future benefit minus the present value of current and

future costs.

(a)

(b)

Journal of Clean Energy Technologies, Vol. 3, No. 4, July 2015

318

.

N

0tt

t

r)(1

CFNPV (5)

where tCF represents the expected net cash flow; N

denotes the lifecycle of the investment project and r

represents the discount rate.

If the NPV is positive, the project can add shareholder

value, or the project can reduce shareholder value.

Internal rate of return (IRR) is the discount rate that equates

the present value of overall capital inflows to the present

value of overall capital outflows. If the IRR of a project is

greater than the rate of return required by EV service

company, service providers should invest in the project, or

service providers should not invest in the project [8].

.)1(

...)1(1

02

210 N

N

IRR

CF

IRR

CF

IRR

CFCF

(6)

Dynamic investment pay-back period is the time that the

net income of the project will take to compensate for the

entire investment. It is an indicator that can assess the

recycling capacity of project investment.

.1j

lzt

Z

ZNP (7)

where tP represents the dynamic investment pay-back period;

zN denotes the year when the positive present value of

cumulative net cash flow appears; lZ represents the present

value of net cash flow in the year before zN and

jZ denotes

the present value of net cash flow in zN year.

V. CASE STUDY

The paper studies the technical and economic evaluation of

the EV charging network planning scheme in Hangzhou city

according to the situation of EV and charge-swap facility. The

paper makes a three-tier structure service network planning

scheme as an example. There are 3 types of EVs in the paper:

taxi, official vehicle and private car. The situation of EV and

charge-swap facility is described below.

TABLE III: THE PRESENT RULE OF EV OPERATION

(a)

Vehicle types Taxi

Number of vehicles 500

Daily average driving mileage[km] 400

The number of working days every year 365

(b)

Official vehicle Private car

500 200

50 40

260 300

The number of every kind charge-swap facility is decided

according toTable III.

A. Technical Evaluation of the Service Network

The three-tier structure service network planning scheme

can supply service for 3000 EVs every day. The area of

planned district is 700 square kilometers and the service

radius is 2.5 kilometers.

B. Economic Evaluation of the Service Network

The paper uses redundancy to increase the number of

batteries in order to ensure that battery can meet the charging

demand of EVs. The redundancy of taxi, official vehicle and

private car are 2, 1.2 and 1.2, respectively. According to the

current data, the price of a battery is 7500 yuan considering

the government subsidy. The battery investment is 55.2

million in the first year. At present, the life of the battery is 5

years, so batteries should be exchanged in the sixth year. The

paper supposes that the price of a battery will increase to

15000 yuan when the government subsidy is canceled

according to the developing trends of battery industry. The

battery range will increase to double its original one and the

charge-swap demand will be reduced by half. The battery

investment is 110.4 million in the sixth year. Every

charge-swap facility will reduce 3 workers in the sixth year

because that the workers can handle the machine skillfully.

The every investment in construction period is decided

according toTable I,Table II and Table IV.

TABLE IV: THE THREE-TIER STRUCTURE SERVICE NETWORK PLANNING

SCHEME

(a)

Facility 100chargers station

The number of Facility 4

(b)

200chargers station 400chargers station CCS BSS

6 2 1 22

TABLE V: ESTIMATES OF EVERY INVESTMENT IN CONSTRUCTION PERIOD

[MILLION]

(a)

Investment types Battery investment Infrastructure

investment

Investments 55.2 238

(b)

Associated power

network investment

Equipment

maintenance

cost

Battery

transportation

cost

Labor

cost

21.6 2.61 12.85 15.9

The service price per kilometer is 0.5 yuan in the first five

years of the lifecycle of the project and the earning is 40.95

million every year. The service price is 0.7 yuan in the rest

period and the earning is 114.66 million every year.

TABLE VI: CASH FLOW EVERY YEAR IN THE LIFECYCLE OF THE PROJECT

[MILLION]

(a)

Years First Second Third Fourth

Total investment 314.8 0 0 0

Earnings 40.95 40.95 40.95 40.95

Costs 31.35 31.35 31.35 31.35

Taxes 2.457 2.457 2.457 2.457

Net cash flow -307.66 7.14 7.14 7.14

Present value of

net cash flow -307.66 6.74 6.35 5.99

Present value of

cumulative net

cash flow

-307.66 -300.92 -294.57 -288.58

Journal of Clean Energy Technologies, Vol. 3, No. 4, July 2015

319

(b)

Fifth Sixth Seventh Eighth Ninth Tenth

0 110.40 0 0 0 0

40.95 114.66 114.66 114.66 114.66 114.66

31.35 26.10 26.10 26.10 26.10 26.10

2.457 6.8796 6.8796 6.8796 6.8796 6.8796

7.14 -28.72 86.18 81.68 81.68 81.68

5.66 -21.64 57.57 54.32 51.24 48.34

-282.92 -304.38 -246.81 -192.48 -141.24 -92.89

(c)

8 Twelfth Thirteenth Fourteenth Fifteenth

0 0 0 0 0

114.66 114.66 114.66 114.66 114.66

26.10 26.10 26.10 26.10 26.10

6.8796 6.8796 6.8796 6.8796 6.8796

81.68 81.68 81.68 81.68 81.68

45.61 43.03 40.59 38.29 36.13

-47.29 -4.26 36.34 74.63 110.75

The IRR of the planning scheme is 9.57% and the dynamic

investment pay-back period is 11.89 years.(Shown in Table V

and Table VI).

VI. CONCLUSION

The service radius is 2.5 kilometers and The IRR of the

planning scheme is 9.57%. The planning scheme is

executable. The EV service company can adjust the

constrution of the charge-swap service network according to

the technical and economic evaluation model. The

construction of charge-swap service network should combine

the profitability with the the actual operating situation in the

future. There are several further work directions from this

research. Firstly, the evaluation model would be more

accurate if more EV charge-swap facilities are taken into

account. Secondly, the evaluation model would think about

the environmental factors.

ACKNOWLEDGMENT

The author thanks the Hangzhou Power Supply Company

in China for the support on this study and for the further

cooperation.

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Junhai Wang was born in Zhejiang Province, China,

in 1971. He obtained his B.Sc. and M.Sc. degrees

from Zhejiang University in motor and control.

He is a senior engineer in Hangzhou Power Supply

Company in Zhejiang provincial electric power

company, Hangzhou, China. His research interests

include power grid planning and design management

and electric vehicle charge-swap facilities operation

management.

Lingling Ming was born in Taian Province, China, in

1989. She obtained her B.Sc. degree from University

of Jinan in 2012. She is currently pursuing the M.Sc.

degree with School of Electrical Engineering,

Shandong University, Jinan, China.

Dayang Yu is an associate professor worked in

Laboratory for the Synergistic Dispatch of the

Decentralized Electric Power Grid, School of

Electrical Engineering, Shandong University, Jinan,

China.

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